[BUGFIX] Fix array_merge when creating FAL access rights

The arguments of array_merge need to be changed, otherwise
the default settings always win.

Change-Id: Ic430e5fdc2f8e5ec868ec2f5a7c0dd21c28a408c
Fixes: #44429
Releases: 6.1,6.0
Reviewed-on: https://review.typo3.org/17446
Reviewed-by: Mattias Nilsson
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel
Reviewed-on: https://review.typo3.org/17479